How do you define central lung cancers when considering SBRT?

Interestingly, I have never fully subscribed to the 2.0 cm "no-fly zone" concept and it was based on the need to ensure the safety of patients in our early experience. If one looks at the literature, the original All-Japan study did not differentiate between central and peripheral locations. The original dose escalation studies we did in Indianapolis were done long before the no-fly zone and in my experience, toxicity was rare. Often the "lobar collapse" can be attributed to mucous plugging comm...

I follow IASLC ART committee recombination (Chang et al., PMID 25514807) and define "central lesion" as within 2 cm of critical structures including bronchial tree, esophagus, heart, major vessels, spinal cord, and brachial plexus. Severe toxicities have been reported with these critical structures and effort should be made to minimize/avoid ablative dose.

Definitions are nice for studies and publications. However, for managing individual patients, I contour the PBT to the end of the lobar bronchi, stopping at the orifices to the segmental branches. I then expand the PBT + 10 mm with a dummy volume to see its proximity with the PTV. At this point, I decide on whether to prescribe 10 Gy x 5 or 4 Gy x 15.